Development of an automatic, closed-loop control system for implanted rotary blood pumps based on real time analysis of ventricular dimensions is proposed. Preliminary in vivo tests using commercially available ultrasonic sonomicrometry transducers placed within the left ventricle (LV) of a calf demonstrated that rotary pumps can be controlled to eliminate potential problems associated with them such as: (a) blood damage due to cavitation caused by negative pump inlet pressures, (b) ventricular wall collapse causing tissue damage and blocked blood flow to the pump, and (c) insufficient pump flow rates. We propose to develop concepts and evaluate the feasibility of a reliable, chronically implanted sonomicrometry transducer/lead system that remains stably positioned within the LV with minimal propensity for migration. Ultimately, such a transducer/lead system will be used as an integral part of an automatic, closed-loop control system for implanted rotary blood pumps. We expect this control system to significantly improve the efficacy and safety of treating Congestive Heart Failure (CHF) patients with rotary blood pumps by eliminating current problems associated with such pumps. PROPOSED COMMERCIAL APPLICATIONS: CHF affects millions of Americans and is the number one financial drain on the US medical system. The only effective treatment is heart transplantation, but here are only about 3,000 donor hearts available per year. Small, implantable rotary blood pumps have been commercially developed to meet this need, but an associated, clinically acceptable, automatic control system has not been reported. The proposed research will allow this enormous need to be filled by providing a control system that enables the safe, efficacious, and reliable use of rotary pumps. The estimated annual market is in excess of$ 15 billion in the US alone.